Session: 04-01-02 Leak Detection and Monitoring - Part II

Paper Number: 86011

86011 - Rapid Leak Detection on Slurry Lines by Negative Pressure Pulse Detection With Distributed Fibre Optic Sensing 

Slurry is a suspension of solid particles in liquid and pipelines can be used to move ore or waste material from mining operations across large distances – typically in remote locations where access is difficult. The nature of slurry means that conventional mass-flow and statistical based leak detection systems are poorly suited to leak detection as the physical properties of the slurry can vary with time. In this paper we present and discuss the use of an in-service external leak detection system - provided by distributed fiber optic sensing (DFOS) - where three isolated incidents have occurred. The incidents were highlighted by the client and details surrounding them have been anonymised in order to allow us to share them.External Leak Detection Systems (LDS) based on Distributed Fiber Optic Sensing (DFOS) offer the potential to significantly reduce the overall amount of spilled product before a leak is detected and localized. Over the past few years OptaSense has undertaken and presented the results from large-scale leak detection trials in pseudo-controlled environments. These results demonstrated near-instantaneous leak detection performance by detection of negative pressure waves (NPWs) for leaks with very small flow rates. Such a system has been installed on a slurry pipeline for the past 3 years and since installation there have been three unique leak events identified by the operator. At least two of these events are estimated to have had a leak flow rate of less than 50 LPM. Notably, in one of the incidents the operator noted that there was no surface evidence of the leak when they went to inspect the location.Each of the leak events shared a common characteristic: the recurrent generation of localised NPW signals. This characteristic is suggested to result from the blocking and unblocking of the leak orifice by the solid material. Slurry is often environmentally unfriendly and as such, the ability to rapidly detect leaks is of great importance. In each case, the system detected the presence of the initial NPW within seconds meaning that detection occurred before more than a few litres had leaked. A further requirement is that nuisance alarms are kept to a minimum. This is desirable in any system but is particularly important for slurry lines as the solid material can fall out of suspension and cause blockages if the pipeline is shutdown. The recurrent NPW events provide an ideal signature with which to rapidly detect and positively discriminate leak events with.

Presenting Author: Alasdair Murray OptaSense

Presenting Author Biography: Alasdair obtained a Masters degree in Physics at the University of Exeter in 2010 before completing a PhD with the Electromagnetic and Acoustic Materials group at the same university in 2014; His thesis was on the subject of the Airborne and Underwater Response of Acoustic Structures. In the same year, Alasdair joined QinetiQ to work with the Acoustic Stealth Materials department. In 2018, Alasdair joined OptaSense as a Senior Data Analyst where he works across multiple business areas. In this role, Alasdair is engaged across engineering, data analysis, research, software development and sales teams where he supports the interaction, analysis and development across departments. Some of the key areas that Alasdair is involved include Pipeline Leak Detection, Rail and Traffic movement, and Infrastructure monitoring.